1. Field of industrial application
The present invention relates to a microwave dielectric ceramic composition, more particularly, to a microwave dielectric ceramic composition which has a high Q value and relative permittivity and also has a temperature coefficient within the range of practical use. The present invention is also concerned with a microwave dielectric ceramic composition which can be produced easily by firing. The microwave dielectric ceramic composition of the present invention will be used for dielectric resonators in the microwave frequency region, microwave IC substrates, and impedance matching for microwave circuits.
2. Prior art
A microwave dielectric ceramic composition (simply referred to as a dielectric ceramic composition hereinafter) tends to increase in dielectric loss with the increasing frequency. Therefore, there is a demand for a dielectric ceramic composition which has a high Q value in the frequency region of microwave.
Known dielectric ceramic compositions include those of ZrO.sub.2 --SnO.sub.2 --TiO.sub.2 system and BaO--TiO.sub.2 system, sometimes with a part thereof replaced by any other element. (See Japanese Patent Publication No. 37807/1989.) These known products, however, suffer from a disadvantage of low Q and relative permittivity, undesirable temperature coefficient, and poor sinterability. In addition, there is a demand for a new dielectric ceramic composition which is different in components from conventional ones and can be easily produced with good sinterability.